allowable pressure rating for a 2" x 3/4" reducer?

[kmg1983]

Let me first explain the scenario...

Currently, we do Cavern Integrity Tests on underground oil storage caverns periodically. When doing so, nitrogen is purged from the wellhead into a frac tank. Connected to the wellhead is a 2" x 3/4" reducing fitting with internal threads which is immediately connected to a 2" hammer-type coupling and then that is connected to 2" hose into the frac tank.

My question is...I know that the hammer-type coupling is rated at 2000psi, however, since there is a weak part in the system (the location at which the reducing fitting is threaded to the wellhead), will that location as well be rated at 2000psi? The overall system must be rated for at least 2000psi. Help please

Also, the only information stamped onto the reducer is...
2" x 3/4" S/80 A/SA234 WPBN W8297 GT

Does the number of threads come into account?

 

[BigInch]

Sounds like it should also be at least 2000 psig.

See this one, thread378-191203

If you still have more questions, just ask.

http://virtualpipeline.spaces.msn.com

 

[TBP]

I've never seen a screwed fitting marked "S/80", only butt weld. Normally for screwed steel fittings, I'd expect to see "3000", "6000", etc.

 

[IVNJ]

To expand on TBP's comment, A234WPB is the Spec for carbon steel butt-weld fittings. It has been my experience that weld fittings do not have female (internal) threads. You could have a swage nipple with a male thread, or more likely you have a forged steel fitting with female threads - ASTM A105/105N. The forges steel fitting will be rated 2000, 3000, or 6000#.
Go to

http://www.bonneyforge.com

for more details in forges steel fittings and Hammer (Lug) unions.

 

[kmg1983]

I apologize...I made a mistake in describing the situation...

The reducer is 2" x 3/4" S/80 A234 WPBN with EXTERNAL threads.

How do I determine the MAWP for this fitting?

 

[dcasto]

Per ANSI B31.3 all threaded piping 1 1/2" or less must be sch 80. Sch 80 pipe in 3/4" to 2" is rated between 2400 psi to 3400 psi. The weakest point is the 2" end rated at 2400 psi. The threads must match ANSI Asme B1.20.1 Pipe Threads.

 

[kmg1983]

I understand that the piping itself is schedule 80 and is rated around 2400psi, however, does the threaded portion fall under that as well? I figured the MAWP for the threaded portion may well be less, due to the fact that it is a "weak" point in the system.

 

[dcasto]

No, the threads do not lower the rating if they are cut to the standard above. Think about your casing in the well, did you derate it for the collars?

 

[kmg1983]

Well, to be honest with you, I'm new to the industry, recently graduated in Mechanical Engineering, and was presented with this question.

We have flexible hose rated at 2000psi connected to a hammer-type coupling, which is then connected to the 2" x 3/4" reducer. The individuals heading this want to make sure that the couplings/fittings on either end of the flexible hose are also rated for 2000psi.

So for the 2" x 3/4" Sch. 80 A/SA234 WPB reducer, it is rated for at least 2000psi, including the externally threaded portion?

 

[dcasto]

Yes. I'd assume the threads were cut to the standard. There should be about 3 threads showing in the male end (pipe)when made up and about 3 unmade up threads on the female end of the connection.